End play eliminating means for lens tubes



April 11, 1950 c; M. LEE

END PLAY ELIIIINA'IING MEANS FOR was TUBES Filed Aug. 13, 1947 r v z 4 present invention;

nun PLAY ELmiNA'rmG MEANS FOR LENS TUBES Application August 13, 1947, Serial No. 768,351

i The present invention relates to photography, and more particularly to a lens mount primarily designed for use on a camera.

In many cameras, focusing is accomplished by moving one or more of the lens cells axially relative to the mount. Such movement may be accomplished by merely sliding the movable cell in and out of the mount. However, in the better types of cameras, the movable cell is spirally moved by means of a threaded connection between the cell and the mount. For obvious reasons, it is desirable that the play or back-lash be eliminated in the threaded connection; but, as is well known, it is quite difficult and costly to make such a connection which is free from end play but which will permit the ready and easy movement of the cell for focusing.

The present invention has as its principal ob- Ject the provision of an end play eliminating means-which effectively removes the end play but permits freedom of movement of the focusing member.

A further object of the invention is the provision of an end play eliminating mechanism which is simple, rugged, of few parts, and highly effective in use.

' the parts of the end play eliminating mechanism when in adjusted position.

Claims. (Cl. ss-sn To these and other'ends, the invention resides in certain improvements and combination of parts, an as will-be hereinafter more fully described, the novel features being pointed out in ithe claims at the end of the speclflcatidn.

used with the end play eliminating device of the Figure :1 is an'enlarged longitudinal sectional view through a portion of a lens mount, showing the relation of the ring of 13 8 1 5913 I-With the threads of the movable lens cell;

Figure 5 is a partial longitudinal sectional view through a lens mount, showing a modifie'd 1 end 0mm STATES PATENT ornca 2 play eliminating device arranged for parts in adjusted relation;

Figure 6 is a partial longitudinal view through the mount showing the relation of the end play eliminating means to the thread of the movable lens cell, showing the manner in which end play is eliminated, yet permitting freedom of movement of the adjustable lens cell for focusing.

Similar reference numerals throughout the various views indicate the same parts.

As the present invention relates only to a mechanism for eliminating end play in the threaded connection along which the movable focusing lens cell or cells move, only so much of the lens mount will be illustrated and described as will be necessary to a full and complete understanding of the present invention. As the mechanism of the present invention can be used with a wide variety of lens mounts, the mount constructions shown herein are merely illustrative and not intended as limitations.

Figure 1 shows one embodiment of an end play eliminating means used in connection with a mount of the type-in which focusing is accomplished by movement of the front lens cell only. As such forms of focusing mechanisms are old and well known, details thereof are not shown. Sufllce it to say that the front lens cell H carries a front lens l2 and is provided with an external thread l3 which engages a corresponding thread on an annular part or member M, to be holding the hereinafter more fully described, to provide a threaded connection with the mount so that the front cell H and lens I! may be moved axially relative to the other lenses, only one of which is shown at l5, to focus the mount. The lens is is mounted in a cell l6 which is preferably, but not necessarily, connected to or formed integral with the annular member I. It is contemplated, however, that the cell l6 may be connected to the mount separately from the member I4. The latter is provided with an external thread H by which the member 14 and cell It may be secured in position in the mount. It is thus apparent, from an inspection of Figure 1, that the member ll provides a support for the focusing cell II which is moved in and out of the mount along the threaded connection between the cell H and member M. v I

In cameras of this ,type, particularly high grade cameras, itis desirable to have a threaded connection for the mount l I which is free from endplay or back-lash so as to secure accurate positioning of the mount, as will be readily apparent to those familiar with the art. However, it is quite diflicult as well as costly to provide such a threaded connection which is free from backlash. The present invention overcomes this difficulty by providing an adjustable member which cooperates with the cell supporting member II to eliminate effectively any back-lash or end-play between the cell and its supporting member ll, yet permitting the cell to be easily and readily screwed in and out of the member II for focusing.

To secure this result. the threaded portion 13 of the cell II has positioned thereon an annular axially adjustable member or ring 20 which engages the thread l3 of cell ll over a number of threads, as clearly illustrated in Figure 1. In assembling, the supporting member ll, with the cell It and lens I5, is screwed into the mount until the lens is properly positioned. The cell H, with the ring positioned thereon, is then screwed into the member H by reason of the thread l3 and the corresponding thread of the member I. The ring 20 is then moved to the right along the thread l3 until the right face 2| of the ring abuts and tightly presses against an aligned face 22 formed on the left end of the member [4. The parts are then in the position shown in Figure 6. In this position, the rin 20 and part I press against each other so that the ring 20 urges member N to the right to cause the right face 23 of each thread thereon to engage tightly with the right face 24 of each of the threads I3, see Figure 6, thus leaving any thread play between threads at the left face as shown at 25. On the other hand, the member l4 reacts on the ring 29 and causes the left face 26 of each thread on ring 20 to tightly engage and wedge against the corresponding face 21 of the thread l3, see Figure 6, leaving any play between the ring 20 and mount l' at the left threaded face, as shown at 2B.

Thus the member 54 and ring 20 are forced in opposite direction and into engagement with opposite faces of the thread l3 so as to effectively remove any end play in the threaded connection, yet permitting complete freedom of movement of the cell I! along the threaded connection for focusing. The member 14 is provided with an annular portion which overhangs the ring 20 and has the periphery thereof formed with a plurality, in the present instance five, of spaced open end slots or notches 30. The ring 20 is provided with a radially extending rib or plate 3|, the periphery of which is formed with a plurality of teeth or lugs 32. When the ring 20 has been screwed into abutting relation with the member M, as shown in Figures 1 and 6, one of the lugs 32 will register with one of the notches 30, and thisregistering tooth is then bent over, as shown in Figures 1 and 2, so as to extend into the notch to connect the ring 20 to the member H to hold the parts in unitary adjusted position to eliminate end play in the threaded connection. The threads on the ring 20 are the same pitch as the threads l3 and the correspondin; threads onv the part I, and when the ring 28 and member H are connected, as shown in Figure 1 and above described, the two parts form in effect a single unitary support for the cell II and provides a threaded connection on which the cell may be moved for focusing. Thus the support for the lens II also provides means for eliminating back-lash or end-play in the threaded connection.

In order to secure the desired result, a novel arrangement of lugs and notches are provided, as shown in Figure 2, the member ll being formed ill with five notches 30 and the plate 3| having a large number of teeth or lugs 32. However, the number of teeth or lugs 32 is of such a number as not to be evenly divisible by the number of notches 30 so that a vernier effect is secured. The result is that when the ring 20 has been moved to its proper position to engage member 14, only one tooth 32 will be in exact registry, or relatively close to such registry, with one of the notches 30 so that the engagement of ring 20 to member II by the inter-engaging of the lugs 32 and the registering of notch 30 can be secured without destroying or reducing the effectiveness of the end-play eliminating feature, the advantage of which will be readily apparent.

In the arrangement shown in Figure 1, and above described, the ring 20 has a length equal to several of the threads I3. A modified ring structure 35, as shown in Figures 3 and 4, is made from an annular sheet of metal or similar material which has a thickness which is substantially less than and about half the pitch of thread II. as clearly illustrated in Figure 4. This ring 35 is deformed so as to have an axial dimension which is equal only to the pitch of the thread I3 so that it engages only a single thread. This modified ring 35 is threaded on to the thread l3 and is adjustable to cooperate with the member I4 in the same manner as the above-described ring 20 to remove end-play in the threaded connection. The ring 35 is, however, much thinner than the ring 20 and extends only along a single thread of the threads l3.

The locking rings 20 and 35, as shown, are made preferably of metal. It is contemplated, however, that these rings may be made of a plastic material so that when a heated member is applied to the projecting teeth 32 the latter may be bent over so as to engage in the notches 30, otherwise the parts are the same as those described in connection with the rings 20 and 35.

Figure 5 shows a modified end-play eliminating mechanism for use in the type of lens mount in which an inner lens barrel, with the various lens elements, is moved for focusing. In this embodiment, the various lens elements, only one of which is shown at 31, Figure 5, are mounted in a lens barrel 38 which is axially movable relative to the mount to move all the lens elements as a unit for focusing. Means, not shown, is connected to the lens barrel to rotate the latter. An annular member or sleeve 39 has an end thereof provided with an external thread 40 for connecting the member in fixed position in the mount. The other end of the member 39 is formed with an internal thread II which engages an external thread 42 of corresponding pitch on the barrel 38 to provide a threaded connection between the barrel and the member, as clearly illustrated at Figure 5. The member 39 corresponds with the member l4, Figure 1, and serves both to support the movable lens barrel 38, and cooperates therewith to provide the threaded connection used for movin the barrel axially for focusing.

In or der to eliminate back-lash or end-play in the threaded connection, the embodiment shown in Figure 5 provides an annular member, ring, or sleeve 43 which is positioned within and concentric with the fixed member 39. The left end of ring 43 is provided with an internal threadedportion 44 which is the same pitch as and which engages the thread 42 on the lens barrel 38, When the ring 43 is screwed to the left along the thread 42, the left end 45 of the ring will abut a shoulder 46- formed on the fixed member 39 and along which the thread of said tube is moved adjacent threaded portion ll thereof. Thus. during focusing, said support comprising a memwhen the fixed member 38 and adjustable ring ber fixedly positioned in said mount, and a ring 43 are in this position, the parts tend to force concentric with and adjustable relative to said each other in opposite dnections, in a manner 5 fixed member and engaging and cooperating similar to the parts illustrated in Figure 6, to therewith to take out end-play in the threaded take up any end-play or back-lash between the connection between said tube and support, and thread 42 and threads 4! and 44. When the locking means separate from said threads for con; member 39 and ring 43 are :in adjusted position necting said ring to said member after adjuste to eliminate back-lash or ends-play, radially m merit. l I aligned holes 41 and may be drilled into the, 5. In a lens mount, the combination with an member 39 and ring 43; respectivelyg- A-screw externally threaded lens carrying tube adapted 49 is then threaded into the hole 41 of the I to be moved axially of said mount for focusing, member 39 and-has a portion 50 which extends. a support for said tube-positioned in said mount into the hole 48 of the ring to connect the memand formed with a thread which is engaged by her 39 and ring 43 to form a unitary structure and'along which the thread of said tube is moved which serves both to support the lens barrel 38 during focusing, said support comprising a memand also to provide a thread along which the ber fixedly positioned in said mount, and a ring barrel may be moved for focusing. Thus the threadedly engaging said tube and adjustable ring 43 may be broadly considered with'the fixed therealong and into abutting relation with said memberf39 as a support for the barrel. Also 2 member and cooperating with the latter to urge member 39 and ring 43 eliminate baclg-lash said member and ring into holding relation with end-play between the barrelfandf'tssupport opposite sides of the thread of said tube to take out end-play between said tube and support, and 1 means forconne'cting' said ring to said member at its periphery after adjustment.

' 6,,In-a lens mount, the combination with an externally threaded lens carrying tube adapted torbemoved axially of said mount for focusing, of 'fa r'nember secured in position in said mount ndj-js'upportingsaid tube, a thread formed on 41 claiinz 1 a v, saidfmember and engaging the thread of said 7:1.1 In a ien mountg the ,combinatlon it .a tube to provide athreaded connectionby which externally threadedlens ca ying tube adapte said tube may be moved relative to said member to be moved "axially of. saidv mounsr rfree s ng of a ;pair;of threaded tube-supportingjnember positioned insaid mount andjfelilgag ing' it thread of said tube, said member bein ,mo

forffocusing, a threaded ring carried by said tube and-"adjustable relatively thereto so as to be myed into tight contacting relation with said I member-to cooperate therewith to take out endrelativelyalong-the threadof saidtub' playin said threaded connection, and means coengaging cgx'iperatingv relation-,toit' re 11 end '-operating with engaging members formed on and play between sad threads, connecting saidring to said member after ad- I memb r for p i 'q j justment' to form. therewith a unitary threaded g support for said tube.

In a lens mount, the combination with an externally threaded lens carrying tube adapted to" be movediaxially of said mount for focusing, i ofjjagisupport for said 'tube positioned in said mount, said support comprising a pair of concentric'rnembers formed with threads which enage and; along which the thread of the tube rnoveslwhenfocusing, said members being positioned'jinztight abutting relation so as to press ally against opposite, sides of the thread of said tube to take .out'end-play between the threads of said tube and support but to permit said tube 7 ing positionqffy.-- e d 2. In allensjfmou'nt, thecombina ion;with an externally threaded len's'earryin'g', tube adapted to'be moved axially of said mount-for m ing; 'of .a support for 'saidtubei positionedfiinsaid mound, said support comprisingfa pair-off mem-L bers'fo rmedWith-threads,whicliengage andaiong-fl which the thread-of the tubemoves'whenfocus-i ing,' said members being adjustable 'irelatively along the threadof said tube t'dtaKe-outaend play i between thethreads of the ,tube 'bers, and means formed from said nier'n er I dependent of :s'aid tln eadsgfor' conn members in adjustedpositioni; 21:1.

7 3. Ina lensmountpthecombination with-an" externally threaded-lens carrying tube; adaptedgf' to'be-moved'axially'of said mount-j for "focu sing, of a member secured in position-in saidmeunt. t a abuttmgremtmnand supporting said'tube,1"aTthread' formed on' .9 1 n a s mountt combination Wlth an said member and engaging the thread of said a rn threaded lens carrymg tube adapted tube to provide a threaded connectionbyewhich tahe of said mount for focusing.

1 said tube may be m'ove'd, rela't'iveto said niember 1 29 3, PPP for said tube p loned in said for f0cusing,,a threaded ring-concentric with's'aid' fl mo l Saidpp comprismg a Pair of conmember engaging the thread of said gtufle a d as centric membersform'ed with threads which enmovable therealong.andlintofabutting zcoo"erat f fl e-and alongwhich the thread of the tube ing relation with saidmember-to keen id moveswhen focusing, said members being adplay in said threaded,Jco'nn' justable-along said tube and into tight abutting 'means independent-loi aid relation to move the thread of one member axially ing said ring and fme rnb "andinto engagement with one side of the'thread :QL-IIn a lensmo'unt; th combination, it of if's"aid' tube to move the thread of the other ,.externally.threadj en carrying tube' adapte memberhxially and into engagement with the tobe moved axially ,saidnio'uiiti"for;focusing,' other-side of the tube thread, said engagements serving-to take out end-play between the threads I wupp f r aid" ib 'iw oee z ns d'm i.

7aiidiformedwitli; i-tn ad; inch is riga' 'ge said tubegand support but to permit movement forffocusingmovement, and interlocking means .on said members for connecting said members I td'mo've freely along the threads of said support of said tube relative to said support for focusing, and means formed on said members for connecting said members in said engaging relation.

9. In a lens mount, the combination with an externally threaded lens carrying tube adapted to be moved axially of said mount for focusing, of a pair of threaded tube-supporting members positioned in said mount and engaging the thread of said tube, said members being movable relatively along the thread of said tube and into cooperating relation to take out end-play between said threads, and vernier means formed from said members for connecting said members in adjusted position.

10. In a lens mount, the combination with an externally threaded lens carrying tube adapted to be moved axially of said mount for focusing, of a pair of threaded tube-supporting members positioned in said mount and engaging the thread of said tube, said members being movable relatively along the thread of said tube and into cooperating relation to take out end-play between said threads, one of said members being formed with a plurality of peripheral notches, and peripheral teeth formed on the other of said members, one of said teeth being bendable into one of said notches to connect said member.

11. In a lens mount, the combination with an externally threaded lens carrying tube adapted to be moved axially of said mount for focusing, of a pair of threaded tube-supporting members positioned in said mount and engaging the thread of said tube, said members being movable relatively along the thread of said tube and into cooperating relation to take out end-play between said threads, one of said members being formed with a plurality of peripheral notches, and

, peripheral teeth formed on the other of said members, the number of teeth being such as not to be evenly divisible by the number of notches so as to provide a vernier effect between said teeth and notches so that when the members are adjusted only one tooth and notch will be in registry, the tooth being bent into the registering notch to connect the members.

12. In a lens mount, the combination with an externally threaded lens carrying tube adapted to be moved axially of said mount for focusing, of a member secured in position in said mount and supporting said tube, a thread formed on said member and engaging the thread of said tube to provide a threaded connection by which said tube may be moved relative to said member for focusing, a ring threadedly engaging the said tube and movable into engaging relation with said member to cause the threads of said member and ring to engage opposite faces of the thread of said tube to take end-play out of said threaded connection, said member being formed with a plurality of spaced peripheral notches, and a plurality of peripheral teeth formed on said ring, the number of teeth being such as not to be evenly divisible by the number of notches so as to provide a vernier effect between said teeth and notches so that when said member and ring are in engaging relation only one tooth and notch will be in registry, the tooth being bent into the registering notch to connect said memher to retain them in engaging relation.

13. In a lens mount, the combination with an externally threaded lens carrying tube adapted to be moved axially of said mount for focusing, of a member secured in position in said mount and supporting said tube, a thread formed on said member and engaging the thread of said tube to provide a threaded connection by which said tube may be moved relative to said member for focusing, a threaded ring carried by said tube and movable into engaging relation with said member and cooperating therewith to take out end-play in said threaded connection, said ring having a thickness substantially equal to half the pitch of the thread of said tube, and means for connecting said ring to said member.

14. In a lens mount, the combination with an externally threaded lens carrying tube adapted to be moved axially of said mount for focusing, of a member secured in position in said mount and supporting said tube, a thread formed on said member and engaging the thread of said tube to provide a threaded connection by which said tube may be moved relative to said member for focusing, a threaded ring carried by said tube and movable into engaging relation with said member and cooperating therewith to take out end-play in said threaded connection, said ring being formed from sheet material of a thickness substantially equal to half the pitch of the thread of said tube and having a thread length of one pitch, and means carried by said ring for connecting the latter in adjusted relation with said member. 7

15. In a lens mount, the combination with an externally threaded lens carrying tube adapted to be moved axially of said mount for focusing, of a member secured in position in said mount and supporting said tube, a thread formed on said member and engaging the thread of said tube to provide a threaded connection by which said time may be moved relative to said member for focusing, a threaded ring carried by said tube and movable into engaging relation with said member and cooperating therewith to take out end-play in said threaded connection, said ring being formed from sheet material of a thickness substantially equal to half the pitch of the thread of said tube and having a thread length of one pitch, said member being formed with a plurality of spaced peripheral notches, and a plurality of bendable teeth formed on the periphery of said ring, the number of teeth being such as not to be evenly divisible by the number of said notches so as to provide a vernier effect between said teeth and notches when said ring engages said members to position only asingle notch and tooth in registry, the tooth being bent into the registering notch to connect the ring and member in adjusted relation.

CHARLES M. LEE.

REFERENCES CITED The following references are of record in the h file of this patent: 1

UNITED STATES PATENTS 

